1. Field of the Invention
This invention relates to a fiber-optic sensing system for measuring the curvature, especially for measuring the curvature of an elongated cavity of an object.
2. Description of the Prior Art
Curvature measurement is important in some fields but hard to perform. For example, in root canal treatment, the measurement of root canal curvature is very useful but complicated to make.
Root canal treatment involves the removal of diseased canal tissue and affected canal wall with super-elastic Ni—Ti rotary file. Due to the curvature of root canals, the rotary files are under rotating bending condition at work, which incurs an alternate tension and compression in the files. Such an alternating loading will lead to fatigue failure. Fracture of rotary file inside the canal is highly undesirable as it is difficult to take the fractured part out. It is therefore useful if one can predict the remaining life of a rotary file. To achieve this purpose, it is important to know the degree of curvature of the root canal.
Conventional method to measure the curvature of root canal employs X-ray radiography. Owing to the three dimensional nature of the canal, more than one radiograph from different directions are needed to obtain a realistic picture of the curvature. However, obstruction form other teeth may interfere with the image. Furthermore, X-ray radiography involves expensive equipment and radiation hazard.
Accordingly, an objective of the invention is to provide a fiber-optic sensing system for measuring curvature, especially for measuring the curvature of a small and elongated cavity such as root canal. This technique for measuring the curvature of the root canal is not only cheaper and more expedient than the conventional X-ray technique, but also it involves no radiation hazard.